(1) Field of the Invention
The present invention relates to an electrophotographic image forming apparatus, and in particular to a toner supply container for supplying toner to a developer in the image forming apparatus.
(2) Description of the Related Art
In general, in an electrophotographic image forming apparatus, such as a fax machine, copying machine, and printer, image formation is performed in the following manner. A developer supplies toner to an electrostatic latent image formed on a photoreceptor to develop the electrostatic latent image, and the developed toner image is transferred onto a recording sheet and thermally fixed to the recording sheet.
Usually, the toner is stored in a large-capacity toner supply container, and the toner supply container is configured to supply only a required amount of toner to the developer according to toner consumption.
At the time, an amount of toner to be supplied from the toner supply container to the developer needs to be accurately controlled. This is because an insufficient amount of toner results in poor image formation due to a lack of toner in the developer, while an excessive amount of toner results in a problem like a toner jam.
Consequently, in the conventional technology, it is common to separately provide a toner supply mechanism capable of quantitatively controlling supply of toner in a supply channel from the toner supply container to the developer. For example, Japanese Patent Application Publication No. 2005-99593 (Patent Document 1) discloses a structure in which a coil spring that has approximately the same diameter as an inner diameter of the supply channel is provided in the supply channel from the toner supply container to the developer. And, by controlling rotation of the coil spring, an amount of toner supplied to the developer is adjusted.
However, with the above-mentioned structure disclosed in Patent Document 1, in order to supply toner to the developer, there is a need to provide (i) a first mechanism for discharging toner from the toner supply container to the supply channel, and (ii) a second mechanism for supplying the discharged toner to the developer while quantitatively controlling supply thereof. This structure prevents an apparatus from being downsized. In addition, it becomes an obstacle to reducing cost because many components and many assembly processes are required.